String Handling in XPCOM

#include "Sample.h"
#include "nsStringAPI.h"
#include <stdio.h>


//This macro automatically adds the nsISupports entry
NS_IMPL_ISUPPORTS1(CSample, ISample)

CSample::CSample()
{
	/* member initializers and constructor code */
}

CSample::~CSample()
{
	/* destructor code */
}

/* long Add (in long a, in long b); */
NS_IMETHODIMP CSample::Add(PRInt32 a, PRInt32 b, PRInt32 *_retval)
{
	*_retval = a + b;
	
	return NS_OK;
}

/*  string ReverseString(in string s); */
NS_IMETHODIMP CSample::ReverseString(const char *s, char **_retval)
{
	char sTemp[256] = {'\0'};
	
	int nLen = strlen(s);

	*_retval = (char*)NS_Alloc(sizeof(char)*256);
	for (int i = 0; i < nLen; i++)
	{
		sTemp[i] = s[nLen-1-i];
	}

	strcpy(*_retval, sTemp);		
	
	return NS_OK;
}

/* AString ReverseAString (in AString nStr); */
NS_IMETHODIMP CSample::ReverseAString(const nsAString & nStr, nsAString & _retval)
{
	nsAutoString strAuto;
	strAuto.Assign(nStr);
	nsAutoString strAutoTemp;

	int nLen = strAuto.Length();
	
	wchar_t wchTemp[256] = {'\0'};
	
	for (int i = 0; i < nLen; i++)
	{
		wchTemp[i] = strAuto[nLen-1-i];		
	}
	
	_retval.Assign(wchTemp);


	return NS_OK;	
}

/* wstring ReverseUnichar (in wstring nStr); */
NS_IMETHODIMP CSample::ReverseUnichar(const PRUnichar *nStr, PRUnichar **_retval NS_OUTPARAM)
{
	nsAutoString strAuto;
	strAuto.Assign(nStr);

	int nLen = strAuto.Length();
	*_retval = (PRUnichar*)NS_Alloc(nLen*sizeof(PRUnichar));

	PRUnichar nStrTemp[256] = {'\0'};

	for (int i = 0; i < nLen; i++)
	{
		nStrTemp[i] = strAuto[nLen-1-i];		
	}

	wcscpy(*_retval, nStrTemp);		
	return NS_OK;
}

/* ACString ReverseACString (in ACString nStr); */
NS_IMETHODIMP CSample::ReverseACString(const nsACString & nStr, nsACString & _retval NS_OUTPARAM)
{
	nsCAutoString strAuto;
	strAuto.Assign(nStr);
	nsCAutoString strAutoTemp;

	int nLen = strAuto.Length();
	
	char chTemp[256] = {'\0'};
	
	for (int i = 0; i < nLen; i++)
	{
		chTemp[i] = strAuto[nLen-1-i];	
	}

	_retval.Assign(chTemp);


	return NS_OK;
}